The CAS Registry Mumber 159336-93-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,9,3,3 and 6 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 159336-93: (8*1)+(7*5)+(6*9)+(5*3)+(4*3)+(3*6)+(2*9)+(1*3)=163 163 % 10 = 3 So 159336-93-3 is a valid CAS Registry Number.